ARABIAN JOURNAL OF GEOSCIENCES, vol.14, no.23, 2021 (SCI-Expanded)
The East Anatolian Fault Zone (EAFZ) with an average length of 500 km is one of the most seismically active regions of Turkey, and many major earthquakes have occurred along this fault zone. The earthquake of 24 January 2020 (Mw = 6.8) with the epicenter in Sivrice (Elazig) occurred on the EAFZ and caused loss of life and property. This study was carried out to investigate the Coulomb stress changes before and after the Sivrice mainshock by using 89 earthquakes (M >= 4.5) with different depth ranges (7.5, 15, 22.5, 30 km) that occurred in the EAFZ between 1997 and 2020. Coulomb stress change maps were created using the Sivrice (Elazig) mainshock and subsequent earthquakes. The maps showed that the stress continued in the northeast and southwest directions and caused a positive Coulomb stress change. According to the Conrad discontinuity depth calculation obtained from the thermal investigation covering the EAFZ and its immediate surroundings, a value of 21.2 km was obtained. While there was no stress increase at depths deeper than 20 km before the Sivrice mainshock, there was a stress increase up to 30 km after the mainshock. Rigidity of crustal structure is higher between segments 1 and 5 compared to segment 6 according to results of Curie Point Depth (CPD) on the EAFZ. This induced the positive Coulomb stress change along with the fault segments at the deeper depth levels. The high Coulomb stress values were especially observed around the Palu-Hazar Lake and Celikhan-Golbasi segments. Therefore, these segments were defined as the earthquake hazard potential region.